1. Field of the Invention
The present invention relates to fuel vapor adsorption filters, and in particular to fuel vapor adsorption filters that are mounted within an intake air channel and extend across the intake air channel. The intake air channel is connected to an engine, e.g., an internal combustion engine, in order to adsorb fuel vapor within the intake air channel when the engine has stopped.
2. Description of the Related Art
Japanese Laid-Open Patent Publication No. 2002-276486 teaches a known fuel vapor adsorption filter. As shown in FIG. 7, a fuel vapor adsorption filter 90 of this publication is constituted by activated carbon granules 91 interleaved between holding layers 94 made of non-woven fabrics. The activated carbon granules 91 are bonded to the holding layers 94 by adhesive layers 92. In addition, the holding layers 94 are covered with heat-resisting nets 96. The heat-resisting nets 96 keep flames from not directly affecting the holding layers 94 of the fuel vapor adsorption filter when the engine has backfired.
However, if the mesh of the heat resisting net 96 is not fine enough, flames produced by an engine backfire may directly affect the holding layers 94, which are made of non-woven fabrics, through the openings of the net 96. On the contrary, if the mesh of the heat resisting net 96 is too fine, the resistance against the flow of the air through the net 96 may increase, causing an insufficient flow rate of intake air to be supplied to the engine.